Recent Developments in Perturbative QCD: Q^2 Evolution of Chiral-Odd Distributions h_1(x,Q^2) and h_L(x,Q^2)

Abstract

After reviewing QCD definitions of the chiral-odd spin-dependent parton distributions $h_1(x,Q^2)$ and h_L(x,Q^2), I will summarize the main feature of the recent two results in perturbative QCD: (i) Next-to-leading order $Q^2$ evolution of h_1(x,Q^2). (ii) Leading order Q^2 evolution of the twist-3 distribution h_L(x,Q^2) and the universal simplification of the Q^2 evolution of all the twist-3 distributions in the large N_c limit.

Comments: 17 pages in Latex. figures are included as eps files. Invited talk presented at ``QCD Corrections and the New Physics'', October 27-29, 1997, Hiroshima, Japan. To be published in the proceedings. (ed. by J. Kodaira et al.) Figures are properly included by epsbox.sty